The LWF Blog
Facilities Management & Fire Safety – Fire Extinguishing Equipment – Part 6February 8, 2017 11:36 am
In this blog series for those who work in Facilities Management and who have a responsibility for or interest in fire safety, we have been covering the types of fire extinguishing equipment and the potential for use in differing fire situations. In Part 5, we discussed the use of powder extinguishers and in this blog, we are going to look at carbon dioxide extinguishers.
We are all aware that a fire needs oxygen in order to continue to burn and a carbon dioxide extinguisher works to displace oxygen and impose a thermal load on the flames of a fire. The carbon dioxide gas is stored within the extinguisher as a liquid under high pressure, so while the extinguisher may contain either 2kg or 5kg of the agent, the containing cylinder can be much heavier with the typical gross weight being between 5kg and 12kg.
While the additional weight of such an extinguisher might imply that it will extinguish a fire most effectively, in fact, it has an extinguishing performance significantly less than other types of extinguisher for most types of fire. It is, however, the most appropriate for use on electrical equipment if the equipment itself must avoid damage or complete loss. For this reason, it is common to find them in those premises in which valuable electrical equipment is housed.
A carbon dioxide extinguisher must not be used in a confined space as the gas contained within is toxic and capable of asphyxiating the user and any other persons present in that area. While caution is necessary in very small spaces, the amounts contained within the extinguisher are not dangerous in normally sized areas of commercial and industrial buildings.
The handling of a carbon dioxide extinguisher cannot be described as ‘user friendly’ as they are quite heavy in relation to their ability to extinguish fires and they also are very noisy when used. During discharge, the discharge horn itself can become very cold and if gripped tightly for a prolonged amount of time can even cause frostbite in the operator. For this reason, some extinguishers are produced with a discharge horn made from a thermally insulating material and it is wise to check this before purchase.
Any staff who might be expected to use this extinguisher should be prepared in advance for the correct method of discharge, the handling of the canister and the resulting noise. Additionally, the effective distance of the discharge is only around 1m and so it will be necessary to approach the fire quite closely, which of course, can be hazardous.
In part 7 of this series, we will cover all other agents available in a fire extinguisher. In the meantime, if you have any queries about your own facilities or wish to discuss this blog series, please contact Peter Gyere in the first instance on 0208 668 8663.
Lawrence Webster Forrest is a fire engineering consultancy based in Surrey with over 25 years’ experience, which provides a wide range of consultancy services to professionals involved in the design, development and construction and operation of buildings.